Understanding the impacts of land use land cover (LULC) changes on hydrology, ecosystemrnfunctions and services is indispensable not only to identify challenges and targeting interventionsrnbut also for watershed management planning measures. However, there is no comprehensivernstudy on the impacts of LULC changes on hydrology, ecosystem functions and services withrnrespect to the past and future periods in the Upper Blue Nile basin of Ethiopia. This study wasrnintended to comprehend the impacts of LULC changes on hydrology, soil erosion, sediment yieldrnand ecosystem services in the Andassa watershed of the Upper Blue Nile basin during the 1985-rn2015 periods, and predict its impact in the coming three decades of the period from 2015 torn2045. The hybrid land use classification technique for classifying time series Landsat imagesrn(1985, 2000 and 2015); the Cellular-Automata Markov (CA-Markov) model for prediction of thern2030 and 2045 LULC states; the Soil and Water Assessment Tool (SWAT) for hydrologicalrnmodeling; the Revised Universal Soil Loss Equation (RUSLE) model for estimating the rate ofrnsoil erosion; the Sediment Delivery Distributed (SEDD) model for sediment yield modeling; thernmodified ecosystem services valuation model for exploring the changes in ecosystem servicesrnwere employed. The different layers of the spatiotemporal changes on the LULC were the basisrnfor examining the changes in hydrology, soil erosion, sediment yield and ecosystem services. Thernresults showed that in the past three decades, cultivated land and built-up areas significantlyrnincreased while areas occupied by natural vegetation such as forest land, shrublands andrngrasslands dwindled at a rapid rate. The predicted results suggest a continuation of the trendrnunless management interventions are made today. The LULC changes, which had occurredrnduring the period of 1985 to 2015, had increased the annual flow (2.2%), wet seasonal flowrn(4.6%), surface runoff (9.3%) and water yield (2.4%). Conversely, the observed changes hadrnreduced the dry season flow (2.8%), lateral flow (5.7%), groundwater flow (7.8%) and ETrn(0.3%). The 2030 and 2045 LULC states are expected to further increase the annual and wetrnseason flow, surface runoff and water yield, and reduce the dry season flow, groundwater flow,rniiirnlateral flow and ET. The LULC changes have also increased the annual soil erosion rate fromrn35.5 t ha-1 yr-1 in 1985 to 55 t ha-1 yr-1 in 2015, and sediment yield from 14.8 t ha-1 yr-1 in 1985 torn22.1 t ha-1 yr-1 in 2015. The prediction result also shows that the increases in soil erosion andrnsediment yield are expected to continue in the 2030 and 2045 periods. The LULC changesrnoccurred between 1985-2015 periods has also reduced most of the provisioning, regulating,rnsupporting and cultural services. If the LULC changes are continued as a usual case businessrnscenario, most of the services are expected to reduce between 2015-2045 periods. The change inrnhydrological components, soil erosion, sediment yield and ecosystem services are a direct resultrnof the significant transition from the vegetation to non-vegetation cover in the watershed. Thesernsuggest an urgent need to regulate the LULC changes in order to maintain the hydrologicalrnbalance, to arrest the expected increase of soil erosion and sediment yield, and to reduce thernexpected loss of ecosystem services.